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Background

Intraductal carcinoma-in-situ of the breast, commonly referred to as DCIS, is a pathologic diagnosis that is occurring with increasing frequency in recent years. This apparent rise in incidence correlates with and reflects the more widespread use of mammography in today's society, particularly in the identification of early, localized DCIS that would have otherwise remained undetected on physical exam. Issues regarding appropriate management of patients with mammographically-detected DCIS include the outcomes with limited breast surgery (i.e.: lumpectomy) and the possible role of postoperative breast irradiation in achieving maximum disease control.

This study aimed to evaluate whether radiation therapy following lumpectomy for early localized DCIS had a benefit compared to lumpectomy alone.

Materials & Methods

Eligible patients had DCIS detected either on physical exam or mammography.

818 eligible women entered between 10/1/85 and 12/31/90.

All women underwent lumpectomy with "removal of the tumor and a sufficient amount of normal breast tissue so that specimen margins were histologically tumor-free".

Cumulative 8-yr incidence of all first events other than IBT was NOT significantly different in two arms: 12.5% vs. 11.0% (p=0.96)

Overall, 14 breast cancer-related deaths: 10 in radiation group and 4 in surgery only group

Conclusions

This 8-year update of data collected under protocol NSABP B-17 continues to show a benefit to post-lumpectomy ipsilateral breast irradiation in the management of patients with localized, mammographically-detected DCIS. This benefit consists primarily of a reduction in cumulative incidence of ipsilateral breast tumors (IBTs), both invasive and noninvasive types. Of note, the reduction in incidence of invasive IBTs was greater than that of noninvasive IBTs, although both reductions were statistically significant. There was no significant difference observed in incidence of locoregional and distant events. Finally, the paper concludes that at the present time, there are not any reliable clinical or pathologic predictors of IBT recurrence following lumpectomy alone for DCIS. Until such discriminants are identified and available, the authors would support the use of postoperative radiation therapy for all patients with localized DCIS based on the results of this trial.